Abstract

Objective – As data on the predictive characteristics of diabetes-associated autoantibodies for type 1 diabetes in the general population are scarce, we assessed the predictive performance of islet cell autoantibodies (ICA) in combination with autoantibodies against insulin (IAA), glutamic acid decarboxylase (GADA), and/or islet antigen 2 (IA-2A) for type 1 diabetes in children with HLA-defined disease predisposition recruited from the general population.

Research design and methods – We observed 7410 children from birth (median 9.2 years) for β-cell autoimmunity and diabetes. If a child developed ICA positivity or diabetes, also the three other antibodies were measured in all samples available from that individual. Persistent autoantibody positivity was defined as continued positivity in at least two sequential samples including the last available sample.

Results – Prediabetic ICA positivity was observed in 1173 subjects (15.8%), 155 of whom developed type 1 diabetes. With ICA screening 86% of the 180 progressors (median age at diagnosis 5.0 years) were identified. Positivity for four antibodies was associated with the highest disease sensitivity (54.4%) and NPV (98.3%) and the lowest negative likelihood ratio (0.5). The combination of persistent ICA and IAA positivity resulted in the highest PPV (91.7%), positive LR (441.8), cumulative disease risk (100%), and specificity (100%). Young age at seroconversion, high ICA level, multipositivity, and persistent positivity for IAA were significant risk markers for type 1 diabetes.

Conclusions – Within the general population the combination of HLA and autoantibody screening resulted in disease risks that are likely to be as high as those reported among autoantibody-positive siblings of children with type 1 diabetes.